Pontiac Grand Prix Catalytic Converter And ABS Codes

Check engine light codes problem with my 2002 Pontiac Grand Prix GT. 3.8L non supercharged. ABS, Track Off and Service engine soon. GM Computer codes  C0045, C0046, C0245, P0303, P0420, P0172.

Reason for code P0420 is because I don’t have a catalytic converter. Ever since I retrieved the code P0303 I have changed all of the spark plugs,fuel pressure regulator, fuel injector for cylinder 3 and switched around coils but still got the code for cylinder 3 misfire.

I only get a misfire when i step on the gas and when i do this my SES starts to flash. OBD code reader reads P0303 cylinder 3 misfire. To correct the problem i have changed out all 6 spark plugs, didn’t change the wires because they are working fine. I have switched up the coils to see if it was the problem. So i switched them up and stepped on the gas and again i got a blinking SES light and code reader gave me P0303. I changed the fuel injector for cylinder 3 and still no solution.

I also changed the fuel pressure regulator and the oxygen sensor behind the engine on the manifold. I also noticed that after i changed the spark plugs i looked at the one from cylinder 3 and it had little cracks and looked kind of smokey. I changed it and a few days later the same thing happend. As for the ABS and Track Off light on I got the codes C0045, C0046 and C0245. What do these mean? What could the problem be for my misfire?

Spark Plug Failure Causing Engine Misfire

Don’t be so sure the plug wire on #3 is good. Several reasons- A misfire under acceleration (load) is a telltale sign of a spark problem. Hard acceleration puts a heavy load on the ignition system- not so much in the injector.

After changing plugs, that #3 had little cracks ? That means the plug is bad. Small cracks in the white porcelain means it is arcing through, and that is your problem. The plug wire is either scratching the porcelain, or is causing arcing. Replace that wire, and see if the plug is damaged again.
Spark Plug Inspection
ABS code C0045- left rear wheel speed circuit
ABS code C0046- left rear wheel speed circuit
The c0245 is speed sensor frequency problem.

Okay well i got rid of my abs codes. I checked the sensor and it was not plugged in, so that took care of that. As for my misfire well i changed out the wire and no longer had it misfire when i stepped on it. I couldn’t believe it was just the wire but every now and then when i step on it, it does miss but it does not do it like how it used to. Why is this?

You may have another plug wire that is weak. Not misfiring enough to cause a light or set a code.
Suggest changing all of them.